Introduction:
Ectropion is characterized by the eversion of the eyelid margin away from the globe. This condition most commonly affects the lower eyelid. This outward eyelid turning is not serious but may lead to multiple complications.
The prevalence of ectropion is around 3 %. Different factors like genetic and acquired factors may cause this pathological condition. Among the acquired factors, paralytic ectropion is the second most common factor caused by injury to the seventh cranial nerve. Clinical assessment of the underlying pathological condition is needed for proper diagnosis. Several modern treatments have now been employed to treat such cases.
What Are the Types?
Ectropion can be of two types. These are:
1. Congenital: Congenital ectropion can be caused by:
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Blepharophimosis Syndrome: This condition is caused by a mutation of the FOXL2 gene and is characterized by narrowing the eye-opening, droopy eyelids, and increased distance between the inner corners of the eye.
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Euryblepharon: This is an autosomal dominant disorder. This condition is associated with diseases like Kabuki syndrome (a congenital problem associated with mental and physical growth) and blepharo-cheilo-dontic (BCD) syndrome (a congenital disorder affecting eyelids, lips, and teeth). Enlarged palpebral fissures due to the excessive vertical separation of the temporal aspect of the palpebral fissures are the characteristic feature of this condition.
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Down's Syndrome: This is caused by the trisomy of the presence of an extra copy of the 21 chromosomes. It is characterized by physical and mental growth retardation.
2. Acquired: Acquired ectropion is caused by:
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Involutional Ectropion: This is caused by age-related changes in the peri-ocular tissues (tissue around the eye). Disinsertion of the lower eyelid muscles and increased horizontal laxity are responsible for this disorder.
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Cicatricial Ectropion: It is caused by vertical shorting caused by the anterior lamella of the lower eyelid. It is caused by chemical and thermal burns, scarring due to surgery, and sunburns.
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Paralytic Ectropion: This is caused by impaired function of the seventh cranial nerve, which causes a reduction in the muscle tone of the orbicularis oris.
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Mechanical Ectropion: This is mainly caused by tumors' physical displacement of the lower eyelid.
What Is Paralytic Ectropion?
Paralytic ectropion is caused by palsy of the seventh cranial nerve. The causes of palsy of the seventh cranial nerves are:
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Bell's Palsy: This is a sudden but temporary paralysis of facial muscles on one side of the face. This is caused by trauma, stress, stroke (reduced blood supply in the brain), and viral infections.
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Leprosy is a chronic granulomatous infection caused by the bacteria mycobacterium leprae. This causes severe skin and nerve infections. As a result, facial nerve paralysis and decreased muscle tone is often observed.
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Tumors: Parotid gland or nerve tumors like acoustic neuroma (tumor of the inner ear), cholesteatoma (abnormal growth behind the eardrum), and schwannoma ( tumor of the Schwann cells) may cause facial nerve paralysis.
What Are the Symptoms?
Patients may complain of the following symptoms:
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Excessive watery secretions from the eye.
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Redness of the eye.
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Itching of the eye with a feeling of constant irritation.
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Dryness of the eye.
On examination following details can be observed:
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Assessment of facial symmetry and muscle tone assessment can be done.
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The outward positioned and low lower eyelid margin and visibility of the lower cornea. In extreme cases, tarsal conjunctiva is visible with the presence of keratinization.
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Snap-Back Test: Lower eyelid laxity is measured by this test. For the test, the lower eyelid is pulled downward for a few seconds without the eye blinking. Then it is released, and the time taken by the lower eyelid to return to its original position is noted. In a normal case, the eyelid will reach its original position immediately, known as zero grade. If the time taken by the lower eyelid is two to three seconds, it is marked as grade I. For grade II, the lower eyelid takes four to five seconds. If the time is more than five seconds, the grade is III. The lower eyelid does not return to its original position in grade IV cases.
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Assessment of lateral canthal angle can be done. The lateral canthus is inserted superior to the medial canthus, which forms the canthal angle. In the case of lateral canthal tendon laxity, the lateral canthus is inserted at the same level as the medial canthus. As a result, the 2 to 3 millimeters distance between the lateral canthal tendon and the lateral orbital rim increases. This can be measured through the following tests:
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For the medial canthal laxity test, the patient is asked to look forward and straight, and the eyelid is pulled laterally. In the case of normal displacement, it is limited to 0 mm to 1 mm and termed grade 0. 2 millimeters of displacement are known as grade1I. For grade II, the displacement is 3 mm. More than 3 millimeters displacement is seen in grade III cases. In the case of grade IV, it does not return to its normal position after blinking.
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For the lateral canthal laxity test, the eyelid is pulled medially 0 mm to 2 mm displacement of the lateral canthal corner is seen in grade 0 cases. The displacement is 2 to 4 millimeters for grade I, and for grade II, it is 4 to 6 millimeters. More than 6 millimeters of displacement is seen in grade III cases. In grade, the IV eyelid does not return to its normal position.
What Are the Complications?
This may lead to several complications, such as:
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Chronic Blepharitis - inflammation of the base of the eyelid caused by clogging of the gland.
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Keratopathy - Damage of the cornea.
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Corneal ulceration.
What Is the Treatment?
The treatment for paralytic ectropion depends upon the severity of the condition.
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If the symptoms are mild and paralysis is also not severe, the application of lubricants and artificial tears can be prescribed.
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In moderate cases, tarsorrhaphy can be done. In this procedure, eyelids are partially sewn together to protect the cornea. Lateral canthal straightening is a very effective procedure to treat moderate cases. In this technique, resection of the lateral canthus is done to tighten the eyelid.
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Canthoplasty procedures can also gain lost canthal support in severe cases. This technique involves resuspending the lower eyelid to the lateral orbital rim periosteum along with canthotomy or cantholysis (exposure of lateral canthal tendon). Various modifications have been made to this technique, including the lateral strip or periosteal flap technique (lower eyelid manipulation without distorting lateral canthal angle).
Conclusion:
Diagnosing paralytic ectropion is important to identify the root cause of facial nerve palsy. Paralytic ectropion may lead to serious eye complications like corneal ulceration or dry eye disease (reduced amount of tears in the eye) due to constant exposure to the globe. Modern surgical procedures are helpful in these cases for repositioning the lower eyelid.
